(a) Field of the Invention
The present invention relates to a light emitting diode (LED), and more particularly to a high luminance LED that is capable of being used as a backlight of a liquid crystal display device.
(b) Description of the Related Art
Types of display devices that may be used as a computer monitor or a TV include self-illuminating devices such as light emitting diode (LED) displays, electroluminescence (EL) displays, vacuum fluorescent displays (VFDs), field emission displays (FED), or plasma display panels (PDP). Device types also include non-self-illuminating devices that require an additional light source, such as a liquid crystal display (LCD).
A typical liquid crystal display device includes two display panels on which field generating electrodes are formed, and a liquid crystal layer that has dielectric anisotropy and is interposed between the two display panels. A liquid crystal display device applies a voltage to field generating electrodes to generate an electric field in the liquid crystal layer. The applied voltage is changed in order to adjust the intensity of the electric field in the liquid crystal layer, which adjusts the transmittance of light passing through the liquid crystal layer so that a desired image is displayed.
The light may be provided from an artificial light source, or may be natural light.
An artificial light source for the liquid crystal display, such as a backlight device, typically uses a plurality of fluorescent lamps such as cold cathode fluorescent lamps (CCFLs) or external electrode fluorescence lamps (EEFL), or it may use a plurality of LEDs as light sources.
In display devices, the LED has been spotlighted as the light source for next generation backlight devices, since LEDs have a number of beneficial properties. For example, LEDs are environmentally friendly because they do not use mercury. Additionally, LEDs have long lifetimes, because of their structural stability.
However, in order to generate white light using LEDs, a light emitting chip and a fluorescent unit are used. The fluorescent unit converts the light emitted from the light emitting chip into light with a different wavelength distribution. Since the light emitted from one light emitting chip is converted into light of various wavelengths and used as a light source, the LED has a problem in that its overall luminance is low.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.